Effect of Heat Treatment on Mechanical Properties of Ternary Blended Eco-friendly UHPFRCC

Abstract

The rapid expansions in economic development, urbanisation and above all population have been accompanied by an upsurge in the accidental fire hazard. The fire redundancy of buildings can decrease the risk of damage and injury by improving the safety of residents and also by enhancing the reusability of buildings. In the recent decades, investigations on elevated temperature resistant passive fire protection layers have been progressing with the use of several environmental friendly materials. However, there is an inadequate information on the effect of heat treatment on the ultra-high performance fibre-reinforced cementitious composites (UHPFRCC) containing high-alumina cement (HAC), ground granulated blast furnace slag (GGBS) and fly ash (FA) in conjunction with hybrid fibres (basalt and polypropylene fibres), which could be a potential fire resisting UHPFRCC for the structural members. The effect of heat treatment on the compressive strength and flexural strength of UHPFRCC, made of ternary blend and hybrid fibres, was investigated in this study. Besides control sample, five other UHPFRCC samples were prepared. After 28 and 56 days of normal curing, each of the samples was held at room temperature as well as exposed to 400, 700 and 1000 °C, then tested. Examination of results disclosed that the UHPFRCC with the replacement of 25 % of fly ash with GGBS, in conjunction with hybrid fibres, possessed highest residual compressive strength in the temperature range of 28–900 °C with 48 % of RCS value at 900 °C after 56 days of curing. However, in the range of 28–1000 °C, UHPFRCC with PP fibre and hybrid fibre performed almost equally well with the residual flexural strength value of 36 % at 1000 °C after 28 days of curing.